The number of Nortli American Neoscona species has been reduced to ten. Characters of the male palpus, the epigynmn, and the dorsal abdominal pattern have been found useful in species diagnosis. There are keys to tlie species, and the distributions have been mapped. Although Neoscona species are among the most common spiders in North America and species are found throughout most parts of the world, no thorough study of the group has ever been made. The most important works dealing with the genus are those of F. O. P.Cambridge (1904), who first recognized several North American species and included detailed descriptions of a number of others, and Archer (1941), who listed many of the
THE ORB WEAVER GENUS NEOSCONA NORTH IN AMERICA (ARANEAE: ARANEIDAE) JONATHAN D BERMAN* AND HERBERT W LEVI ABSTRACT The number of Nortli American Neoscona spe- reliable characters for separating the species be found has been reduced to ten Characters of the male palpus, the epigynmn, and the dorsal ab- While it is easy to find differences between individual specimens of Neoscona, dominal pattern have been found useful it cies in species diagnosis There are keys to tlie species, distributions have been mapped and the Although Neoscona species are among common spiders in North America and species are found throughout most parts of the world, no thorough study of the group has ever been made The most important works dealing with the genus the most are those of F O P.-Cambridge (1904), who first recognized several North Amer- ican species scriptions of Archer and a (1941), included number who of listed detailed de- others, and many of the North American species but did not give any indication of how he was able to separate them Because Neoscona includes common spiders, the problem of determining specimens frequently arises in ecological studies In addition, members of the genus have sometimes been used as laboratory animals For these reasons important that it is is that far more reflect difficult to find similarities the common gene pool of species In this investigation it was found that the most dependable character for separating females of the genus is the epigynum together with the color pattern Details of the palpus are the best characters for distinguishing males; the macrosetae of the second tibia are not always reliable Ten species of North American Neoscona were segregated on the basis of these and other characters Most specimens in collections can readily be placed in one of these species and between the species there are gaps in the characters used Occasional specimens are difficult to determine, per- haps because poor preservation removed the color pattern, and because of abnormalities or, perhaps, hybridization Dr J A L Cooke made available the collections of both the American Museum of Natural Histoiy and Comell Universit)', Dr C D Dondalc, the collections of the were Canadian National Museum Other Canadian collections were supplied b\- D J Buckle Dr H K Wallace loaned large collections from Michigan and Florida with ecological data, and Dr W Shear provided specimens and other help Dr H V Weems sent specimens from the Florida nomenclatural problems resolved State * This study was started as a senior thesis for Harvard College by J D B The object vi^as to find characters that can be used in separating The cliaracters carefully species of the genus studied were coloration and pattern, size, epigynum, and spination of the second tibia of males The palpi of the species separated by these criteria later studied in detail by H W L and Bull Mas Comp Zool., Museum 141(8): Dr M Grasshoff loaned 465-500, September, 1971 465 BuUetin 466 Museum of Comparative Zoology, Vol 141, No specimens from the Senckenbergischen Naturforschenden Gesellschaft Dr J G Sheals and Mr D J Clark made it possible for H W L to examine the many types Museum at the British (Natural History) Proszynski of the Polish Academy of Sciences made the Taczanowski collection Dr J available to us, Prof M Hubert of the M Vachon and Mr d'Histoire Paris, Natiu-elle, Museum National loaned many specimens Specimens from the University of Costa Rica were made available by Dr D C Robinson and Mr C E Valerio! Mr D Bixler and Dr R E Leech loaned specimens from personal collections Dr H T Boschung Museum University of Alabama, of Natural History, made Archer of the Gutman Laurie available specimens helped with the draft of the thesis first prepared by J D B., I^orna R Levi edited the final manuscript Dr Peter van Helsdingen was most helpful in discussions about the unusual nomenclatiual complications This investigation was supported by the palpus of the male On the inspiration of Kaston (1948), who distinguished be- tween male Neoscona from Connecticut on the basis of the macrosetae of the second tibia, comparisons of the arrangements and patterns of macrosetae on that leg segment were made During the course of the study, large and often striking variations in the dorsal coloration of the abdomen were noted, and so systematic observations on this character were made, well as as comparisons of ventral abdominal patterns The specific carapace coloration of some spiders and the presence of a coniform spur on coxa IV were noted as incidental of certain others observations The measurements are not expected to be useful in separating species, but were taken to provide supplementary data on species separated by other means Since the abdomen size is particularly variable, depending on how well-fed the spider was at the moment of collection, the carapace Public Health Service Research Grant AL 01944, from the National Institute of Allergy measurements are undoubtedly more useful in comparing species Measurements of and Infectious Diseases less than 10 within 0.2 mm mm INTRODUCTION Although observations were restricted Old World Neoscona was undertaken in order to assess similarities and differences New World fonns Selection of characters The choice of characters to be studied was guided pri- and error, as well as some knowledge of what characters are useful marily by in the trial classification spiders other of groups Although the reasons for it of are not well understood (Mayr, 1963), the structure of the genitalia of both sexes is often a highly specific character in spiders, as well as in a The initial made on the Differences in the structure epigynum proved to be the best Epifiynum primarily to spiders collected from North America (including Central America), the West Indies and Hawaii, some study of between Old and are probably accurate to number of other arthropods observations epigynum were therefore of the female and of the In Neoscona basis for separating females the epigynum may have one or two pairs bulges or none at all These bulges may be positioned either flush with of lateral the ventral surface of the scape, somewhat dorsal to it, or \\'ith either the proximally or distally situated end of each bulge connecting with the ventral margin and the opposite end extending dorsal to it In the two cases, in ventral view, part of each bulge projects beyond the margin and latter part can usually be seen beneath the surface of the scape, as the epigynum in Neoscona tends parent their position, dorsal-ventral, highly were to The number be somewhat trans- of pairs of bulges and both proximal-distal and on the scape appears to be specific obscured, Occasionally however, the bulges especially in Neoscona Spiders (presumably collected specimens their lives) sclerotized that epigyna particularly late in had unusually heavily This pronounced in tendency is N oaxacensis The presence near the parently or absence of a contraction midpoint of the scape is apconstant for a species and is sometimes useful (especially when absent, as most species have it) The contraction seems to be variable in N oaxacensis small epigynal differences such as occur between N arahesca and the much larger N domiciliorum may size of the spider than good specific differences, and therefore the epigynum of an unusually large N arahesca might resemble that of a very small specimen of N domiciliorum Palpus The palpi in male Neoscona are apparently very similar in all species Some differences were noted in the shape and position of the apophysis and paracymbium and median in the location of the termi- nal spine on the median apophysis, but these differences were not consistent and did not appear to be usefully specific Not near the end of the study were palpal characters found more usable than the macrosetae of the second tibia: the shape and attachment of the terminal apophysis, the shape of the embolus witii its lamella, the shape of the conductor and the places where the unusual fused bulb is broken until and the parts are slightly movable against each other Macrosetae of second tibia The arrangement of macrosetae on the second tibia, sometimes in conjunction with other charprovided a useful criterion for separating males In Neoscona there may be one, two, or three rows of clasping macrosetae along the prolateral surface of this leg segment Although the total num- acters, ber of macrosetae varies considerably within a species, their gross pattern, including the number of rows (maximum number of macrosetae abreast), appears to be quite fixed ing macrosetae, In addition to the claspthe second tibia usually Berman and Levi 467 one prominent ventral macroend and two or three large dorsal spines Some Neoscona arahesca and N naiitica can easily be possesses seta the at proximal recognized by striking and characteristic deviations from tibia itself may be Also, the pattern curved, with the prolateral surface concave, but this curvature is quite variable and not especially reliable in It is possible that be more functions of the • most this cases Beatty (1970) reports that during the course of development Although injuries may produce si-^eable variations in the leg macrosetae of Ariadno, it is not likely that such an occurrence would produce a sizeable change in the overall pattern in Neoscona, especially as the clasping macrosetae not appear until the final molt Another possible hazard in using the tibial macrosetae to separate the species is that the number of rows may vary with the size the specimen However, in southern specimens of Neoscona arahesca, which vary considerably in size (total length of the male: 3.9-9.2 mm) and were at first of separated primarily by the presence of a number of ventral tibial macrosetae, large that the number of rows clasping macrosetae remains fixed, although the number and size of the it was noted of macrosetae increases somewhat with the increasing body size As the macrosetae the proximal end of prolateral surfaces are often longer and more variable than the stout, relatixely vmifomi macroat setae of the distal half, in some species it uncertain whether just the distal or all the prolateral setae should be referred to is We as clasping macrosetae have tried to clear, in the descriptions of in- make dividual species, exactly which macrosetae are considered clasping in each case Dorsal abdominal pattern When one gains familiarity with spiders of this group, it becomes possible to recognize most inof most species solely on the dividuals basis of the dorsal coloration of the abdo- men (Plates 1, 2, 3) In some cases tliis coloration can be a reliable specific char- 468 Butletin H Museum of Comparaiwe Zoology, Vol 141, No Neoscona Spiders Berman and Levi • 469 arahesca Walckenaer, designated by F O P.Cambiidge, 1904, Biologia Centrali-Americana, Araneidea, 2: 466 Chinestela Chamberlin, Mus 63: U Proc 1924, S Natl species by nionotvpy C gisti Chamberlin, 1924, 63: 20, pi 5, fig 37, Male holotype witiiout palpi from Soochow, S China, in the U S National Museum, examined 20 Type One palpus marked holotype in the Museum Comparative Zoology, examined (which has since been presented to the U S National of Museum) The the Univ other palpus Utah is presumably in collection Franganillo, 1926, Cuba Contemporare, (161): 14 Type species by monotypy C nidicola Franganilla [:='Neoscona neotheis] Eriovixia Archer, 1951, Amer Mus Novitates, 1487: 34 Type species by original designation CubaneUa 41 Eriovixia rliiniirus (Pocock) [=zAraneus rliinuSYNONYMY ms] Neosconopsis Archer, 1951, Natirr Hist Misc., Chicago Acad Sci., 84: New subgenus Type NEW by monotypy and original designation Neoscona adianta (Walckenaer) [^Araneus species adiantus] NEW SYNONYMY Note Chinesteh gisti is very close to Neoscona l^entzii in appearance Cuhanelki was first synonymised by Franganillo himEriovixia a synonym like those self Plate Neoscono domlciliorum Washington, D C Bottom Fig Top Fig from female Neoscona of female from Florida slightly in has a Carapace Distinct carapace coloration was observed in females of three species In two (Neoscona hentzii and N nautica) it is probably too variable to be of much use, but in N orizahensis it is highly characteristic (Fig 7) and will separate the female of that species The fourth coxa Males of several species can easily be separated by the presence of a coniform spur on the posterior edge of the ventral surface of coxa IV ( Fig ) After lengthy testing, dependable characters have been found that provide clear gaps between the populations (Michener, 1970), and these populations are presumed to be the species Neoscona Simon Neoscona Simon, Araignees, ed 1864, Histoire Naturelle 261 1: Type species: des N considered because the female genitalia are is species flatter being "tail." There is The scape differs Also the abdomen no reason name for a separate genus, unknown male proves to have this distinct from Neoscona to keep unless the characters Neosconops^is, ac- cording to Archer, differs from Neoscona on which the main piece of the median apophysis of the male palpus is situated is wide instead of pedunculate." As far as we could tell, the median apophysis attachment is like that of all other care- in that "the stalk fully examined species and Archer's obser- \ation is The erroneous name Neoscona is of feminine gender Description median eyes In are species the anterior largest or subequal to all posterior medians; the secondary eyes are just slightly smaller The posterior lateral mav be the smallest The anterior median eyes are usually slightly more than eves 470 Museum Bulletin of Comparative Zoology, Vol 141, No their diameter apart, the posterior medians shghtly less than their diameter The height which of the clypeus is sUghtly less tlian the diameter of an anterior median eye The earapace has a longitudinal thoracic groove, \\'hich in males may be extended by a line stretched over most of the carapace It is less distinct in females (Fig 7), and is hidden in living specimens by setae ( Plates The palpus is unique in several ways It seems never to have been described before The cymbium covers the face of the bulb (Figs 1, 4), and has expanded in such a way that most structures are hidden by it The 1-3) first legs are longest, the second, second in length, the third shortest All males have a hook on the distal rim of the venter on the first coxa and have macrosetae on the prolateral surface of the second tibia The abdomen varies in shape: oval Neoscona arahesca, elongate in in N oaxacensis, triangular in N nautica, and with hinnps in N redempta In all, the venter of the abdomen is black bordered on the sides by white spots (Figs 10-13) Males are only slightly smaller than females The Diagnosis longitudinal thoracic groove on the carapace separates all members from Araneiis Together with the fused epigynum and unique palpus (see below) the species are readily separated from related Amneiis All species have a black patch between epigastric furrow and spinnerets, bordered by one or two white spots on the sides Genitalio Both male and female genitalia have structures fused, probably secondarily The epigynum is a simple tongue, the scape completely fused to the base The openings are underneath ( dorsal an indication that most of the may be derived from the base surface), structure Figs The 1-6 left Dorsolateral view palpus of Neoscona Ventral view with has the openings (Figs ( Fig 4) In Aranetis the or less narrow strip in (Y more a is R ) stipes , ( I ) , and embolus cymbium The radix ( E ) have almost immovably in N arahesca (Fig 5) In N oaxacensis (Fig 4) and in N nuuiica (Fig 116) a small hematodocha sc>parates two sclerites, probably the fused stipes and radix Tlie hematodocha is reduced compared to that of Araneus species The embolus (E) is more or less drawn to the side of tube-shaped to conical, out, which the embolus lamella ( L ) is attached The embolus rests against the conductor C and is covered apically by the terminal ( ) apophysis (A) The terminal apophysis is a thin flap in most species; it is much reduced in N nmitica (Figs 118, 119) The conductor is in all a thumb-shaped prostructure, jecting its tip bolus the sclerotized, side of and facing the em- color light in The base of the conductor varies The greatest difference between in shape species is in the shape of the embolus with lamella, the terminal apophysis (seen in apical view), and also the conductor Un- its fortunately, this embolus is completely surrounded by conductor, terminal apophIn Neoscona ysis, and also the cymbium )ieothcis the stipes-radix joint facilitating its recognition In this study the 1-3, 5-6 N arahesca cymbium cleared in Aranetis 14-25) N oaxacensis Expanded, bulb is sclerotized, cymbium was removed Ventral view subventral view Lateral view Expanded, bulb dorsal view Fig Fig Fig Figs Neoscona orizabensis F P -Cambridge, female carapace Neoscona orobesco (Walckenaer), venter of male cephalothorax with Neoscona oaxacensis (Keyserling), fourth male coxa and trochanter 10-13 Scales Abbreviations I, stipes; Female abdomen, ventral view Palpi, 0.1 L, mm; others, 10 N arahesca 1 N legs ooxocensi's beyond 12 coxae N removed neotheis 13 N nautica mm A, terminal apophysis; C, conductor; lamella of embolus; M, median apophysis; DH, R, distal radix; hematodocha; T, tegulum; Y, E, embolus; cymbium H, basal hematodocha; Neoscona Spiders • Bennan and Levi 471 472 Bulletin from at least Museiun of Comparative Zoology, Vol 141, No one specimen of each species drawing However, for routine examination this is not necessary The terminal apophysis is of characteristic shape and one can readily separate Neoscona arahesca from related species by to facilitate looking at it (in apical view, ventral view of the spider with the palpus flexed) It was the decisive factor in synonymizing N minima and N am])esca For the purpose of making the diagrammatic drawings (Figs 26, 27), an outline drawing was first made, then the structure torn off The terminal apophysis is opaque at its base, transparent at its distal margin The individually variable transparent area may at first be confusing to those wanting to use the structure for detennining species The terminal apophysis does not have to be removed for making determinations In N nautica the terminal apophysis is minute seems carefully, to be at of first studied use little in separating species Its general appearance is as in Araneiis diadematus- relatives The shape of the conductor may be large head and S-shaped appearance seem to separate N hentzii from other species The conductor is best detailed useful: Its studied in lateral view The palpal tibia has two setae, one of which may be longer than the other When propelled naturally expanded, the bulb is away from the enclosing cym- The various hardly shift in of the bulb sclerites position Males in collec- have the palpi expanded Neoscona species are among the most common and abundant orb weavers Neoscona arahesca can be ob- tions rarely Natural histonj tained in numbers by sweeping meadows or fields in summer or late summer (in southern Canada and the northern states) I found the European Neoscona large adianta (Walckenaer) just as southern Europe, collecting common it in in every field visited in southern Italy and Dalmatia New England and Wisconsin there one only generation a year (of both Neoscona arahesca and Neoscona hentzii), males maturing in late June and July, females in July and August Collections of In is N oaxacensis suggest that it also has only one generation a year, most adults having been collected between August and November In shape, the egg case varies from a flattened sphere to a lens-shape (of N arahesca and N hentzii), and is covered by some loose silk Kaston ( 1948 ) described that of N arahesca as being about in diameter and containing 280 10 yellow eggs agglutinated in a mass measur- mm ing 9.0 X 5.4 X 3.6 mm Neoscona hentzii egg cases (according to Kaston, 1948) are made of fluffy yellow threads in a rolled One had a large diameter of 12 another one, spherical, had a diameter of mm The first had 1000 eggs, the second 867 The egcfs were oval, measuring up The median apophysis, bium meadow and leaf mm, 0.97 X 1.15 mm We assume that because of its great abundance, every spiderling having a web, Neoscona may be of importance in controlling insect numbers Wei) The webs of N arahesca and N hentzii are vertical Kaston (1948) describes the Neoscona araJ)esca web as having about 20 radii and being 15-45 cm in diameter trated in One with 18-20 Comstock (1940, The hub radii is illus- 530, 531) only one or figs is open, crossed by two threads, imlike webs made by species of Araneiis There are relatively few threads toward the retreat According to Comstock, N araliesca rests in the center of the with the tip of the abdomen ^^'eb pushed through the open space All our observations (and apparently those of Kaston) agree that during daytime N arahesca stays in a retreat to the side of the web, usually in a curled up leaf The web of oaxacensis is illustrated in Plate N Neoscona Spiders Distribution Species • Berman and Levi 473 Neoscona are of found on all continents Unfortunately, many have always been placed in Aranetis The common species found in Europe is Neoscona adianta (Walckenaer), the genof which are much closer to those of North American species than to the cosmotropical N nautica Neoscona 7iautica may be native to the Pacific area, judging by the similar species in this area Other European species belonging to Neoscona are Epeira cnicifera Lucas, 1839 and E hyzanthina Pavesi, 1876, both of the Mediitalia terranean region Species p^roups Neoscona nautica, presumably introduced, is the most distinct species occurring in North America It is the onl)' species in which the male palpus has a minute curved tenninal apophysis; the terminal apophysis of all other species is a flap Also, the females of N nmdica have a short triangular epigynum, shorter than that of other species The three species N oaxacensis, N neothcis and A^ pratensis are The pattern characteristic first two may be similar all is The males of allopatric: N oaxacen- found from California and Texas to South America, N neotheis is West Indian, N pratensis is found in the United States, outside the range of N oaxacensis Of the remaining North American species, Neoscona hentzii (east of the Rocky Mountains to Arizona) is the largest ^nd distinct, utahana (south-central states) and N orizabensis are much it the labora- (Keyserling) The type of this species appears to be lost Key la alike How- smaller than the species and all four have distinct is dorsal abdominal patterns Most illustrations were drawn to the same scale to Neoscona females Abdomen with wavy line lateral distinct hnmps and a (Fig 124), Texas redempta lb 2a arahesca (from Canada to Central AmerN domicdiorum (eastern United sympatric with in Neoscona, but they are believed distinct Misplaced species Neoscona granaden= Araneus granadensis sis ( Keyserling ) ica), ever, N arabesca Neoscona oaxacensis mode Asiatic species were examined and many were found similar to the North American having a scape with a spoon- shaped end following a constriction (Figs 51-53) The male has an S-shaped, short conductor (Fig 55) The genitalia of N States), N of very similar sis is most Web Space between two rods on top is 20 mm, photographed on high contrast film (Courtesy Peter N Witt) of each of the three have a spur on the fourth coxa Their distribution Plate tory Abdomen without hmnp.s and not having a wavy Hne on each side Epigynum witli scape very broad and triangular (Figs 111-115); dorsal abdominal pattern indistinct, dark olive to brown (Fig 2b nautica 120) above 3b Dorsal abdominal pattern of longitudinal bands as Fig 100 or Fig 110 Dorsal abdominal pattern otherwise 4a A median 3a Epigynum not as dark band bordered by a light on each side (Fig 110); epigynum without lateral bulges at midpoint (Fig _101 ) pratensis line 474 4b 5b of Comparative Zoology, Vol 141, No A median white band bordered by two bands (Fig 100); scape with lateral bulges near midpoint ncotheis (Fig 91); West Indies Abdomen subtriangular with a dorsal folium sharply delimited on sides (Fig northern to states south-central 77); utahana Mexico black, 5a Museum Bulletin Abdomen oval or if subtriangular, marked Epigynum without lateral bulges 14-25); abdomen subo\al with mm, than 8.2 mm 6b Epigvnum long with more lateral bulges men or distinct if 43, 59, 78); abdosuboval marked other- total length (north of Mexico) usually more than 8.5 mm, carapace more than 3.7 long mm 7b oval to elongate with median hght band made up of spots (Figs 8890); epigynum with one pair of bulges (Figs 78, 81-83); Cahfomia, Utah, Texas oaxacensis to Peru Abdomen Abdomen triangular or oval with othei"wise; epigynum pairs of bulges 8b 9a Carapace otliei-wise or, if similar, not found in central Mexico Epigynum with one pair of bulges ( Fig 9b 43), abdomen contrastingly marked (Fig domiciliorum 50), eastern U S — Epigynum with two pairs of bulges, the proximal indistinct (Fig 51), abdomen without contrasting markings (Fig 58); east of Rocky Mountains, Arizona „- hcutzii lb 2a to off on its a dorsal folium distinctly sides (Fig 77); south- Abdomen without such utahana 16 a folium Terminal apophysis with sides more or less parallel and a wide notch on distal arahesca end (Figs 26, 27) 6b Terminal apophysis of different shape _ orizahensis 7a Central Mexico 7b Canada, U S and northern Mexico 8a Conductor in lateral view S-shaped (Fig hentzii 55 ) 8b Conductor in lateral view, elongated, with tip and base only slightly curved (Fig domiciliorum 47 ) Neoscona arahesca (Walckenaer) Plate Figures 1-3, 5-6, 1, 125, 126, Carapace chestnut brown with light brown central bands 7), (Fig longitudinal orizahensis Mexico la 15 6) Abdomen with set and marked one or two 8a Key 4, 6a wise; 7a ^ Terminal apophysis a minute curved strucnautica tme (Figs 118, 119) 4b Terminal apophysis a flat flap (Figs 3, 4a 51) (Figs triangular, near central states (Figs dorsal carapace less arahesca less bulb of palpus not attachment of terminal odiei-wise; apophysis (Figs 84, 86); California, Utah, — oaxacensis Texas to Peru 5a posterior black marks at an angle (Figs 34, 35); total length (north of Mexico) usually less than 2.8 Abdomen sclerotized otherwise 6a 3b longitudinal Neoscona males Map 8, 10, 14-42, Epeira arahesca Walckenaer, 1841, Histoire Naturelle des Insectes Apteres, 2: 74 The types are Bosc, Araignee de Caroline illustration, p 13, 5, fig 2, in the library of the Museum National d'Histoire Natiuelle, Paris, and Al)liot manuscript illustrations, figs 331, 446 from Georgia in the British Museum, Natural History Copies in the Museum of Comparatixe Zoology examined McCook, 1893, American Spiders, 3: pi 148, pi Epeira 1, fig trivittata Naturf Ges., 8, pi 2, figs Keyserling, Isis, 6, 7, 1863, Dresden, p 95, 5,